Results

- Complications after cryosurgery with new miniature cryoprobes in long hollow bones: An animal trial

Mean duration of operation was 4 h 22 min, mean duration of
anaesthesia 5 h 13 min. In 18 of 24 cases, the mean pulmonary-arterial
pressure PAP and the mean central venous pressure (CVP) showed no
significant changes at any of the 4 sampling times (Figs. 1 and 2).
The PAP rose in 2 animals while in 4 other cases, the haemodynamics
could not be determined for technical reasons. There was only a
temporary increase of the mean PAP and CVP while the animals were in
the right unilateral recumbent position, but all values normalised when
the animals were shifted to their left side. The heart increased
marginally during the operation (Fig. 3).

Blood gas analysis showed an increase in pCO2 at constant oxygen saturation after the animals were shifted to their right side. In 5 of the animals, the pCO2 remained
slightly higher even after they were shifted to their left side. PH,
base excess, electrolytes and lactate showed no changes at any sampling
time. Hemoglobin decreased marginally (Fig. 4).
The deep body temperature (taken central-venously) before and after
cryosurgery was not obviously related to any single cryoablation, but
it did show a mean decrease of 1.25°C over the course of the entire
operation (Fig. 5).
Clinical follow-up observations yielded no remarkable findings. The
mean time of recovery – i.e., from the end of anaesthesia until the
animals were able to stand up again – was 86 minutes. None of the 24
animals showed any clinically significant respiratory insufficiency.
One animal developed a severe wound infection which required treatment.
The wound was excised and showed secondary healing under antibiotics
(Fig. 6).

Autopsy revealed clean scars in all animals. There were macroscopically
and microscopically no signs of ongoing or resolved osteomyelitis. All
vein samples were free of old or recent thrombi. The lungs were grossly
unremarkable. Histology of the bronchopulmonary arteries showed no
evidence of acute or cronic embolism or thrombus. Thus, none of the
animals had suffered an embolism even at the segment level. Some did
show a marked bronchial pneumonia, although it followed an asymptomatic
course and was therefore of no consequence. No animal showed
spontaneous fractures, and X-rays taken at the end of the trial
revealed no evidence of healed fractures.